Gum disease treatment: can a hyaluronic acid gel regrow bone as well as the standard?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Periodontitis stage III or IV, grade A or B (Tonetti et al., 2017): attachment loss ≥ 5mm, radiographic bone loss extending to to the middle third and beyond, tooth loss ≥4 due to periodontitis, probing depth (PD) ≥ 6mm. * Older adults ≥ 18 years. The number per sex shall be balanced. * Plaque index (PI) \< 1 following initial periodontal therapy and hygiene instructions. * Bleeding on probing (BoP) ≤ 10%. * Only patients with optimal compliance, assessed during etiological therapy, will be selected. * At least a 2-3 wall interproximal bone defect with a radiographically moderate or deep intrabony defect (≥3mm), PD≥ 6mm using a Williams probe on uniradicular teeth or mandibular molars without furcation involvement after non-surgical periodontal treatment. * Vital teeth or teeth with well-performed root canal treatment. * Absence of caries, prosthetic restoration or periapical infection in the tooth to be regenerated. * Absence of systemic pathology. * Negative history of pregnancy. * Signed informed consent. * The participant is willing and able to comply with the necessary visits for the treatments and evaluations scheduled during the clinical study. Exclusion Criteria: * The participant is pregnant, breastfeeding or plans to become pregnant in the next 6 months. * Smoking ≥10 cigarettes/day. * Daily alcohol intake \> 4U. * Chronic illness or reduced mental capacity that may influence compliance with the protocol. * Medications or drugs that alter the patient's healing or with concomitant oral manifestations that, in the opinion of the investigator, could interfere with the assessment of safety or efficacy. * Systemic diseases that may influence treatment such as diabetes mellitus or rheumatoid disease. * Allergies to drug compounds. * Antibiotic intake 3 months prior to the start of the study or systemic condition requiring antibiotic coverage at the time of periodontal treatment. * Periodontal treatment 6 months prior to the start of the study.